Fascinating and Frightening Frilled Shark Facts

It's Named for Its Appearance

The common name of the frilled shark refers to the animal's gills, which form a red fringe around its neck. C. anguineus’ first pair of gills cut completely across its throat, while gills of other sharks are separated.

The scientific name Chlamydoselachus anguineus refers to the shark's serpentine body. "Anguineus" is Latin for "snaky." The shark may be snake-like in the way it catches prey, too. Scientists believe it launches itself at prey much like a striking snake. The shark's long body houses a gigantic liver, filled with hydrocarbons and low-density oils. Its cartilaginous skeleton is only weakly calcified, making it lightweight. This allows the shark to hang motionless in deep water. Its posterior fins may enable it to lash out a prey, which includes squid, bony fish, and other sharks. The shark's jaws end at the back of its head, so it can open its mouth wide enough to engulf prey half as long as its body.

It Has 300 Teeth

The fluffy-looking gills of C. anguineus may appear cuddly, but the cute factor ends there. The shark's short snout is lined with about 300 teeth, lined up into 25 rows. The teeth are trident-shaped and face backward, making it practically impossible for ensnared prey to escape.

The shark's teeth are very white, perhaps to lure prey, while the animal's body is brown or gray. The broad, flattened head, rounded fins, and sinuous body may have inspired the sea serpent legend.

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It's Very Slow to Reproduce

Scientists believe the gestation period of the frilled shark may be as long as three and a half years, giving it the longest gestation of any vertebrate. There doesn't appear to be a specific breeding season for the species, which is unsurprising since seasons are not a consideration deep in the ocean. Frilled sharks are aplacental viviparous, which means their young develop inside eggs within the mother's uterus until they are ready to be born. The pups survive mainly on yolk before birth. Litter sizes range from two to 15. Newborn sharks measure 16 to 24 inches (40 to 60 centimeters) in length. Males become sexually mature at 3.3 to 3.9 feet (1.0 to 1.2 meters) long, while females mature at 4.3 to 4.9 feet (1.3 to 1.5 meters) long. Adult females are larger than males, reaching a length of 6.6 feet (2 meters).

It Poses No Threat to People (Except Scientists)

The frilled shark lives in both the Atlantic and Pacific oceans along the outer continental shelf and upper continental slope. Because the frilled shark lives at great depths (390 to 4,200 feet), it doesn't pose a threat to swimmers or divers. The first observation of the species in its natural habitat wasn't until ​2004, when the deep-sea research submersible Johnson Sea Link II sighted one off the coast of the southeastern United States. Deepwater commercial fishermen catch the shark in trawls, longlines, and gillets. However, the shark is not intentionally captured, as it damages nets.

While the frilled shark isn't considered dangerous, scientists have been known to cut themselves on its teeth. The shark's skin is covered with chisel-shaped dermal dentricles (a type of scale), which may be quite sharp.

The Number of Frilled Sharks Is Unknown

Is the frilled shark endangered? No one knows. Because this shark lives deep in the ocean, it is rarely seen. Captured specimens never live long outside their natural cold, high-pressure environment. Scientists suspect deep-water fishing poses a threat to the slow-moving, slow-reproducing predator. The International Union for Conservation of Nature (IUCN) lists the species as Near Threatened or Least Concern.

It's Not the Only "Living Fossil" Shark

Frilled sharks are called "living fossils" because they haven't changed much in the 80 million years they have lived on Earth. Fossils of frilled sharks indicate they may have lived in shallower water prior to the mass extinction that wiped out the dinosaurs, moving into deeper water to follow prey.

While the frilled shark is a frightening sea serpent, it's not the only shark that is considered a "living fossil." The goblin shark (Chlamydoselachus anguineus) is able to thrust its jaw forward from its face to snatch prey. The goblin shark is the last member of the Mitsukurinidae family, which goes back 125 million years.

The ghost shark broke away from other sharks and rays about 300 million years ago. Unlike the goblin and frilled shark, the ghost shark makes a regular appearance on dinner plates, often sold as "whitefish" for fish and chips.

Frilled Shark Fast Facts

• Name: Frilled Shark
• Scientific Name: Chlamydoselachus anguineus
• Also Known As: Frill Shark, Silk Shark, Scaffold Shark, Lizard Shark
• Distinguishing Characteristics: Eel-like body, a frilly first gill that runs beneath entire head, and 25 rows of teeth
• Size: 2 meters (6.6 feet)
• Lifespan: Unknown
• Region Where Found and Habitat: Atlantic and Pacific Oceans, most commonly found at depths of 50 to 200 meters.
• Kingdom: Animalia
• Phylum: Chordata
• Class: Chondrichthye
• Status: Least Concern
• Diet: Carnivorous 
• Offbeat Fact: Believed to strike prey like a snake. A living fossil that pre-dates the dinosaurs. Believed to inspired the sea serpent myth. Longest gestation of any vertebrate (over 3 years).

Sources

• Compagno, L.J.V. (1984). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Food and Agricultural Organization of the United Nations. pp. 14–15.
• Last, P.R.; J.D. Stevens (2009). Sharks and Rays of Australia (second ed.). Harvard University Press.
•  Smart, J.J.; Paul, L.J. & Fowler, S.L. (2016). "Chlamydoselachus anguineus". IUCN Red List of Threatened Species. IUCN. 2016.